Fast and accurate real-time processing of data signals is desirable in general purpose digital signal processing, consumer electronics, industrial electronics, graphics and imaging, instrumentation, medical electronics, military electronics, communications and automotive electronics applications among others, to name a few broad technological areas. In general, video signal processing, such as real-time image processing of video signals, requires massive data handling and processing in a short time interval. Image processing is discussed by Davis et al. in Electronic Design, Oct. 31, 1984, pp. 207-218, and issues of Electronic Design for, Nov. 15, 1984, pp. 289-300, Nov. 29, 1984, pp. 257-266, Dec. 13, 1984, pp. 217-226, and Jan. 10, 1985, pp. 349-356.
Video signal processing requires the use of Finite Impulse Response (FIR) digital filters for many of the data processing applications. If the sampling frequency is carefully selected, the coefficients of the filters can be small ratios of powers of two or at least simple combinations of powers of two. Real time video signal processing requires that the operating processors receive and process the video signal and the data necessary to emulate digital filters at extremely fast rates. In the prior art a substantial portion of the processing time is consumed in obtaining the sample data from adjacent processors in the array. For example the processors in the array would have to execute a series of instructions to address, read and transfer data located in its next adjacent processor until it reaches the desired location in the array. In a large array, this sequence of transferring the data from one processor to the next until it reaches a desired location is time consuming. If a finite time exists to receive and process the data, a large data retrieval time will of course leave less time for data processing. One technique for performing this processing is to utilize a Scan-line Video Processor (SVP), described in U.S. Pat. No. 5,163,120, assigned to the present Assignee.
A typical SVP is operable to receive a single scan line from a video output between two horizontal blanking periods and then store this in a Data Input Register (DIR). This data is then transferred to a processing element (PE) during a horizontal blanking period, and an algorithm applied thereto during a horizontal sync period, and on a following horizontal blanking period, the processed data is then transferred to a Data Output Register (DOR). The operation is done on a concurrent line-by-line operation and in a synchronized manner. The data transfer from the DIR to the PE must be performed during a horizontal blanking period of the input signal; otherwise, current data and prior data from the previous horizontal scan line in the DIR is read by the PE.
In the application of the SVP to video processing, one algorithm that must be processed is that for performing the chroma demodulation. In processing a conventional demodulation algorithm, the phase of the color burst signal is first detected by a phase detection algorithm to yield phase detected output signals which are then input to phase shift operation for phase shifting the phase detected outputs and then driving a color demodulation algorithm. The detected signals are cyclic signals which typically have some type of noise reduction algorithm applied thereto. Since the gain of the burst signal is relatively small, i.e., approximately 0.286 Vp-p on an EIA specification, the phase detection operation can be greatly affected by external noise, such that any incorrect detection data is output therefrom. Typically, some type of Low Pass Filter (LPF) or Band Pass Filter (BPF) operation is applied for the purpose of noise reduction on the phase detected signals. However, only the low and high frequency noise against the frequency of the phase detected signals can be rejected by the LPF or BPF. Therefore, there exists a need for an improved noise reduction technique for use with chroma demodulation in an SVP environment.